Breast Cancer in Pets. As with humans, beloved household pets can also develop cancer in the breast tissue — known in animals as mammary cancer. In fact, cancer is the No. 1 natural cause of death in older pets. But with a little know-how, animal owners can help catch tumors before they become deadly. “It’s a fairly common cancer, especially in unspayed female dogs and cats,” said Gerald Post, a veterinary oncologist at the Veterinary Oncology and Hematology Center in Norwalk, Conn. “It’s important for owners to spay female animals before the animal first goes into heat, because each following heat cycle increases the risk of developing the cancer.”
Pets with mammary cancer follow basically a similar type of treatment and recovery as humans with breast cancer. However, pet tumors are often not discovered until later, when the cancer has reached a more advanced stage. About half the mammary tumors that dogs develop are noncancerous, which is similar to the ratio of nonmalignant tumors women find in their breasts. In cats, however, 90 percent of mammary tumors are cancerous. Vets say that these types of tumors closely follow the model of more aggressive forms of human breast cancer.
Early Warning Signs for Owners
And cancer in a pet, in some cases, may provide owners with an “early warning system” of sorts. “The age-adjusted rate of cancer is actually higher in dogs and cats than in people,” said Greg Ogilvie, director of the California Veterinary Specialist’s Angel Care Cancer Center. “Pets have genetic factors, but they also live in a more polluted environment, and they have passive smoke exposure.” Part of the problem may be the toxins that find their way into the air, water, and human households, where pets also live. Because humans and animals share the same environment, some animal cancer experts say that our pets may provide a good indicator of the risks of cancer around us.